oxygen species (ROS) generation. This bone resorption by os- teoclasts causes a decline in the content of structural bone and the result is a weaker bone,” the researchers explained.
Tibia and humerus breaking strength Tibia breaking strength has been shown in several studies to be a reliable measurement of bone strength. It is a bone strength trait with high genetic heritability. Betaine had a sta- tistically significant effect on tibia breaking strength. Hens that were fed betaine had higher tibia strength and tibia den- sity than birds that were not fed betaine. There was no effect of betaine on humerus breaking strength, but there was an effect of age. Humerus strength was higher in the hens at 45 than at 70 weeks of age. There was, however, a significant negative correlation between plasma homocysteine level and humerus breaking strength. What was interesting about the humerus bone is that it was the only bone trait that was correlated with homocysteine.
Keel density The keel is one of the bones in the laying hen that is most susceptible to injury or fractures. In this study, there was a positive correlation between homocysteine and keel density. While this was counterintuitive to the researchers’ expecta- tions, they stated, “It could be that the calluses that arise from keel injuries would increase bone density so that weaker keel bones would − somewhat counter-intuitively − have higher density.”
Influence of age In the current study, betaine had a significant effect on reduc- ing plasma homocysteine concentrations at 45 weeks but had no effect at 70 weeks of age. Tibia and humerus strength were higher in the hens at 45 than at 70 weeks of age.
“The effect of betaine through homocysteine may be greater during higher concentrations of bone remodelling, which oc- curs at a younger age during development and high egg-lay- ing periods. Betaine might be less effective as the concentra- tions of homocysteine increases, as the concentration of homocysteine was higher at 70 weeks of age compared to 45 weeks,” remarked the researchers.
Performance and egg quality The researchers’ results suggested that the addition of betaine and phytase in the diet does not significantly affect the devel- opment of the birds and their reproductive system – birds from all treatment groups (betaine and phytase groups) had high production and produced eggs of similar quality. Howev- er, hens fed 1000 FTU/kg of phytase had higher feed intake than those fed the betaine diet or the phytase at 300 FTU/kg.
Conclusion It was concluded that reduction in homocysteine through the addition of betaine leads to an increase in bone strength measurements, especially in the tibia and humerus. Betaine is a potential nutritional strategy for bone strength as it inter- venes in the trans-methylation cycle, resulting in lower plas- ma homocysteine levels. It is also worth noting that the addi- tion of dietary betaine improves bone strength without affecting egg quality or production. As a result, betaine could be used as an intervention tool to alleviate welfare concerns in laying hens. It is also worth remembering that the varia- tions in bone strength observed in laying hens are caused by several factors. The four broad areas (excluding genetics) that could explain variation in and/or increased fractures, inde- pendent of egg production, are the age at first egg, late ossification of the keel, predisposing bone diseases, and inactivity leading to poor bone health.
▶ ALL ABOUT FEED | Volume 29, No. 3, 2021 31
Research shows that the addi- tion of betaine leads to an in- crease in bone strength meas- urements, espe- cially in the tibia and humerus
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